Eidson T H, Edrington J L, Albuquerque M L, Zuckerman S L, Leffler C W
Department of Physiology, University of Tennessee, Memphis 38163.
Pediatr Res. 1995 Jan;37(1):10-4.
Cerebral vasodilation in response to hypotension is necessary to maintain adequate cerebral blood flow. This study in newborn pigs examines the hypothesis that endothelial injury in vivo inhibits cerebral vasodilation in response to hypotension in newborn pigs, thus suggesting that this response is endothelium dependent. Chloralose-anesthetized piglets with closed cranial windows were studied before and after injury caused by light/dye or before and after dye only sham control. Light/dye injury was produced by injecting sodium fluorescein i.v. and passing filtered light from a mercury arc lamp through the cranial window. Measurements of pial arteries and arterioles were made during normotensive and hypotensive periods. Hemorrhagic hypotension (to 50% of the mean arterial control value) caused pial arterial and arteriolar diameters to increase 49 +/- 8% and 66 +/- 8%, respectively. After the light/dye injury, dilation in response to hypotension was absent, whereas dilations in response to isoproterenol and constriction in response to hypertension (3.33 to 4.0 kPa increase in arterial pressure) and hypocapnia were retained. These findings are consistent with the hypothesis that hypotension-induced cerebral arteriolar vasodilation is dependent on endothelial signals influencing adjacent smooth muscle.
对低血压做出反应的脑血管舒张对于维持充足的脑血流量是必要的。这项针对新生猪的研究检验了以下假设：新生猪体内的内皮损伤会抑制其对低血压做出的脑血管舒张反应，从而表明这种反应依赖于内皮。对采用氯醛糖麻醉且开有颅骨视窗的仔猪，在光/染料造成损伤前后或仅进行染料假对照前后进行研究。通过静脉注射荧光素钠并使来自汞弧灯的滤光透过颅骨视窗造成光/染料损伤。在血压正常和低血压期间测量软脑膜动脉和小动脉。出血性低血压（降至平均动脉对照值的50%）导致软脑膜动脉和小动脉直径分别增加49±8%和66±8%。光/染料损伤后，对低血压的舒张反应消失，而对异丙肾上腺素的舒张反应以及对高血压（动脉压升高3.33至4.0 kPa）和低碳酸血症的收缩反应仍保留。这些发现与以下假设一致，即低血压诱导的脑小动脉舒张依赖于影响相邻平滑肌的内皮信号。
